If they balk, then you know where you stand and that information is probably valuable.
A negotiation is not an argument. It is an agreement.
Either you reach one or you don’t.
And if you agree to something that you don’t want to live with, you’re already halfway out the door.
Lets say you want $250k. Ask for $500k. They might be relieved, because they thought you would want $800k.
If your 2nd best option is a job making 200k.. and you ask for 800k and they just say no? Well, being cocky just lost you 200k (you could have asked for 400k).
150% is far more reasonable than 200%. Let's say you won't take below 100k, Co. won't take above 120k, you offer 150k. From the Co.'s perspective, that's 25% difference, it's worth negotiating. If you offer 200k, that's 66% off what you'll take. Co.'s probably thinking, okay, this guy will take 160 maybe 140 but no way they'll really think they can negotiate down to 120.
At bigger companies there aren't incentives to spend tons of time negotiating a candidate down to the top of your acceptable range, so even if they think they can get you down 80k you're out.
You don't counteroffer a candidate you can't afford. And I think you understand intuitively 200% is too much, which is why you go 150%.
So why not skip that step and start more reasonable?